Improvement in armatures for dynamo-electric machines



(J. F. BRUSH. Armature for Dynamo-Electric Machines.

No. 203,413. Patented May 7,1878.

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Q INVENTOR Y -UNITED STATES PATENT OEEIoE.

CHARLES F. BRUSH, OF CLEVELAND, OHIO.

IMPROVEMENT lN ARMATURES FOR DYNAMO-ELECTRIC MACHINES.

Specification forming part of Letters Patent No. 203,413, dated May 7,1878 application filed January 23, 1878.

To all whom it may concern Be it known that 1, CHARLES F. BRUSH, ofCleveland, in the county of Ouyahoga and State of Ohio, have inventedcertain new and useful Improvements in Armatures for Dynamo-ElectricMachines and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it pertains to make and use it, reference being hadto the accompanying drawings, which form part of this specification,

My invention relates to that class of dynamo-electric machines in whichannular armatures are employed, and especially to the armature of suchmachines.

My said invention consists, first, in so splitting or dividing thearmature and insulating its parts from each other as to practically orentirely prevent the induction of currents in the same when it isrevolved in a magnetic field, thus eliminating the principal source ofheat and waste of power in such armatures; second, (when the armature isof such pattern as to make it desirable,) in perforating portions of thesame, both for the purpose of removing superfluous stock of metal, andto increase the heat-radiating surface, and thus favor the dissipationof the heat which is always generated in armatures when in service, anddue to the rapidly-changing magnetism.

In the drawings, Figure 1 represents, in perspective, one form ofannular armature constructed according to my invention; and Fig. 2represents a cross-section of the same.

In both the above f gures the armature is shown naked of its wire anddisconnected from the other parts of the machine. I prefer to constructthe armature from cast-iron, although in this respect I do not limitmyself in any degree, as any suitable metal may be used.

The armature is constructed substantially as shown in the drawings; andconsists primarily of two parts, AA, firmly secured together, with anysuitable insulating material, E, interposed between them. B representsan annular groove formed upon one or both sides of the armature, and,for reasons which will appear, there may be more of these grooves thanare shown, if desirable. O G are depressions in the armature, which, inthe completed machine, are wound full of insulated wire. D D are holespiercing the armature from its periphery to the annular grooves B, andare provided for the purpose already specified.

hen this armature is revolved (in its own plane) in a suitable magneticfield, electric currents will be induced in a direction at right anglesto its circumferential length, and will traverse the wire wound in thedepressions C. It will now be obvious that if such an armature is madeof one solid piece of metal, the

induced currents will also circulate in the armature itself, therebywasting a large portion of the inductive effect of the magnetic fieldand rapidly heating the armature. The insulating material E prevents thepassage of these currents around the entire cross-section of thearmature, and confines them, in greatlydiminished force, to each half ofthe crosssection. These diminished currents are again checked by thegrooves B, (which may properly be regarded as insulating air's'paces,)on the principle that if an electric circuit is broken in one point, theentire current is stopped. The passage of the current is thus confinedto each quarter of the armatures cross-section, and thus becomes soreduced as to be insig nificant.

It will now be obvious that the insulating material E may be replaced bya deep groove, Gr, as shown in Fig. 3 of the drawings, thus leaving themetal of the armature in a single piece, and still accomplishing thedesired end.

Another modification would be to construct the body of the armature fromseparate concentric rings, insulated from each other, placed one withinanother, and thus secured.

I am aware that in previous devices armatures have been constructed of abundle of wires formed into annular shape; but I have found thisdescription of armature not to be practicable.

I am also aware that in Patent No. 189,997, granted to me April 24,1877, I mention incidentally that an armature, instead of being madefrom one solid piece, may be formed from parallel disks or plates; butin this patent I did not specify, nor did I contemplate, any insulationbetween the component disks going to make up my armature; and it willmoreover be observed that the wires composing the armature of Patent No.20,057, of date Octo-' ber 17, 1871, are not specified as beinginsulated from each other; and from my knowledge of the machine referredto in said patent No. 20,057, I know the component wires of its armatureto be naked; but in my present device I provide the novel feature ofinsulating from each other the component parts of my armature; and inthis very important feature resides a radical distinction between thisinvention and any other preceding it of which I am aware.

What I claim is- 1. An annular armature constructed from a single solidpiece of metal, and grooved upon its periphery or sides, or both,substantially as and for the purpose shown.

2. A11 annular armature consisting of two or more plates formed withgrooved sides or peripheries, or both, and insulated from each other,substantially as set forth.

3. An annular armature, provided with holes, perforations, ordepressions D, or their equivalents, substantially as and for thepurpose shown.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

CHARLES E. BRUSH.

Witnesses:

L. L. LEGGETT, J NO. OROWELL, Jr.

